A neuroscientist explained the causes of behavioral changes in dementia

A person with dementia can calmly react to a familiar situation today and worry about it tomorrow. The reason is not necessarily related to the rapid deterioration of the disease: the behavior is influenced by fatigue, physical needs, emotional state and the environment. This was announced on September 24 by Matt Kirkcaldy, senior lecturer at the Wicking Neuroscience Center at the University of Tasmania, at a lecture on behavioral change in dementia.

Why is the behavior changing?

According to Kirkcaldy, human behavior consists of many factors. Among them are habits, physical needs, emotions, understanding of the situation and the time of day. Usually, a person compares these signals: he may be thirsty if he is busy with an important task, or refuse a new occupation if he is tired. In dementia, brain diseases can disrupt the functioning of the systems involved in this process.

He suggested taking into account changes in the level of fatigue, anxiety and stress, as well as the needs that a person could not meet. Even familiar surroundings can be perceived differently if it is more difficult for him to understand where he is and what is happening on this day.

As Kirkcaldy explained, others often assume that an unusual act was a conscious choice of a person. In dementia, such an assessment may be erroneous: behavior changes, including due to impaired brain function. However, it can still express an attempt to cope with a situation or communicate a need.

This approach is also used by researchers helping people with dementia. A review of research published in 2026 considers behavioral changes as a possible expression of unmet needs. The authors found that care measures based on an assessment of such needs and an individual approach were associated with a reduction in the severity of certain behavioral and psychological symptoms.

What role do memory and orientation play in what is happening?

Dementia is usually primarily associated with memory impairment. However, Kirkcaldy emphasized, the ability to remember events also helps a person navigate what is happening. He compared the work of the hippocampus to keeping a diary: thanks to the sequence of memories, a person understands how he ended up in a certain place, what he did before and what is expected of him now.

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If this sequence is disrupted, the usual situation may become unclear. A person sees people and objects around them, but it is more difficult for him to restore the context and choose the appropriate reaction. In Alzheimer's disease, the changes first affect, in particular, areas of the brain involved in the formation of new memories, including the hippocampus. Later, they may extend to areas related to speech, reasoning, and social behavior.

The work of the frontal areas of the brain, which are involved in planning and evaluating actions, is also important. Kirkcaldy compared their role to that of the chairman of a meeting: they help to take into account several motives at once and choose what to do. If this work is disrupted, it may become more difficult for a person to control their reaction or adapt to circumstances.

In the early stages of the disease, a person sometimes tries to compensate for the difficulties that have arisen: he keeps a closer eye on what is happening, tries not to get lost and control his actions. But it takes effort. According to Kirkcaldy, when tired, coping with such a load becomes more difficult, and behavioral changes may be more noticeable.

Why sleep and physical condition are important

Another factor is the body's needs. Hunger, thirst, or cold motivate a person to act. If dementia makes it difficult for him to understand what exactly is causing discomfort, or to find a way to eliminate it, anxiety may increase. Kirkcaldy suggested considering unusual behavior as a possible form of communication that a person needs something.

In the lecture, the scientist also talked about circadian rhythms. The time of day affects alertness and behavior, and in the evening, fatigue can increase difficulties. Anxiety and confusion that occur towards the end of the day are known as sunset syndrome. However, there is no single reason for such changes that is suitable for all patients: sleep, well-being, and surroundings may be important.

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A separate question from the audience concerned sleep and memory. Kirkcaldy spoke about the role of sleep in processing daytime experiences and expressed his opinion on the importance of dreams for learning. Here, however, it is worth distinguishing between the established connection and its explanation. A meta-analysis of the research showed that dreams related to the material studied before bedtime were accompanied by better memory test results. These data alone do not prove that dreams are necessary for memory.

Is it possible to explain the changes only by dementia

At the end of the webinar, Kirkcaldy touched on the impact of concomitant diseases. In particular, disorders of the blood supply to the brain can change the picture of cognitive disorders. Therefore, according to the scientist, the peculiarities of a particular person's behavior cannot be understood only by a general description of Alzheimer's disease or another disease that causes dementia.

In addition, a sudden change in behavior does not necessarily mean the progression of dementia. Pain, lack of sleep, stress, constipation, changes in routine, and certain medications can increase anxiety or cause other changes. The US National Institute of Aging recommends discussing such symptoms with a doctor to find out the possible cause. It is especially important to seek medical evaluation if the changes occur suddenly.

Kirkcaldy stressed that his lecture was devoted to explaining the work of the brain, not clinical recommendations. The main conclusion for the loved ones, in his opinion, is to try to understand what is behind the unusual reaction of a person: what difficulties he is experiencing and what could affect him at the moment.